Method for removing oil lubricant film from steel



United States Patent 3,163,607 METi-Itl l) FM; REMDVHNG 61L LUBRlCANT FILM FRQM STEEL Herbert Ii. Drake, Nazareth, Pa, assignor to Bethlehem Steel Company, a corporation of Pennsylvania No Drawing. Fiied Aug. 2., 1962, Ser. No. 214,186 11 Claims. (Ci. 252 170) This application is a continuation-in-part of application Serial No. 727,280, filed April 9, 1958, now abandoned.

This invention relates to the removal of lubricant film from metals, and more particularly to the application of a specific type of water mixture, or emulsion, in the removal of such film.

In the cold working of metals, wherein lubricants are used under extreme pressure, as in the cold rolling of strip, a rather tightly adherent film tends to build up on the metal surface. This film may result in objectionable metal surface conditions when the cold worked metal is given subseqeunt finishing treatments.

When steel strip is subjected to cold reducing, a lubricant, often palm oil or a palm oil substitute, is applied to the strip before the strip enters the rolling mill. Generally, four-or-five-stand tandem mills are used in the cold reducing operation, and fresh lubricant may be applied before each roll stand. Because of the extreme heat generated in the rolling operation, the lubricant is usually added as an oil in water emulsion, the water having the function of heat dissipation. In spite of the cooling effect of the water, the strip temperature, on certain mills, becomes such that there is often considerable breakdown of various lubricants as the strip passes through the rolls. When the oil breaks down, a rather tenacious film develops on the strip. This film usually contains oil fragments, iron soaps, varnish-like condensation products and some original oil.

When this lubricant film is not removed, or is only partially removed from the strip, serious surface defects may develop during the annealing step which follows cold rolling. Common defects, which show up on the strip after it is removed from the annealing furnace, are carbonaceous deposits, which appear as smudge or dirt over the surface of the strip, staining and carbon edge. Carbon edge occurs as a hard coating actually extending into the metal surface, and it is commonly found near the edge of strip which has been box-annealed in coils. This form of defect can only be removed by abrasives or by bufiing, and portions of strip containing carbon edge cannot be used as prime stock. The so-called dirt, in the form of a carbonaceous deposit, can be removed from the strip by a rubbing action, but its removal adds a costly and time-consuming operation to the production of finished strip.

To insure against rejects, due to the various defects described above, a minimum of lubricant film should be present on the strip during annealing. In practice the film is often effectively removed by a separate washing procedure, which involves unwinding the coil and passing the strip through a hot, strongly alkaline bath, followed by rinsing, drying and recoiling. The strip is then clean and ready for annealing. To avoid this extra procedure, it is often common in the industry to omit the application of oil at some point near the end of the tandem mill and to substitute at this point a diluted solvent emulsion, or a detergent solution. By this means, the amount of oil film left on the rolled metal may be reduced to such an extent that the strip will be relatively clean and can be annealed directly after rolling, without any intervening cleaning step; However, some rolling oils, notably palm oil and tallow based oils, often break down, as noted above, to produce a film stubbornly resistant to all commonly used detergents or solvent emulsions. Detergents or cleaners, which may be effective in the removal of new palm oil, or new tallow-based oils, are often little more effective than water for the removal of the break-down products of such oils. Cleaners composed of loosely emulsified petroleum spirits, or oils, are only partially effective against such breakdown oil films.

An object of this invention is to provide a composition and method for the satisfactory removal of lubricant film from cold-worked metal.

According to the present invention, the lubricant film, which remains on a metal surface after a cold-working operation, can be removed by the application of a water mixture, or emulsion, of certain insoluble fatty alcohols and alcohol derivatives of monoterpenes. The monoterpenes may be acylic or cyclic. I have found that when a water emulsion of the foregoing alcohols or alchol derivatives is applied to the surface of steel strip which has an adherent film composed largely of break-down products of a lubricant, that the film is substantially com-.

pletely removed from the metal surface.

Alcohols which are particularly effective for use in this invention are those Water-insoluble fatty alcohols having from 6 to 18 carbon atoms, including such compounds as hexyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, cetyl, stearyl and oleyl alcohols, and their isomers. Compounds representative of the alcohol derivatives of terpenes are u-terpineol and geraniol. These materials have superior solvent action on'lubricant film break-down products.

An example of a satisfactory treating mixture, composed of an emulsion of an alcohol, is that which contains water and decyl alcohol wherein the weight ratio of water to said alcohol ranges from 500:1 to 5 :1. The emulsion of water and alcohol cleaner may be made by merely mixing the two with rapid stirring. A more practical type of emulsion, however, one which will retain its emulsion characteristics over a sufiicient interval of time, can be prepared by the incorporation of an emulsifying agent. When about 5% emulsifying agent,

based on the weight of alcohol in the mixture, is used, a temporary emulsion is formed. Emulsifying agent in the amount of 10% will produce a more permanent type of emulsion. The temporary form of emulsion is the most etficient in most circumstances, for in this unstable form substantially all of the alcohol is released in a reactive condition, when the emulsion comes in contact with the film-coated metal.

The present invention has proved quite effective in the treatment of cold-rolled strip, the effectiveness being illustrated by the following examples:

Example I A mill test was run using an emulsion formed by a mixture of the following ingredients:

Parts Water so-decyl alcohol 1.0 Emulsifier 0.05

The emulsifier was a blend of three volumes of lgepal (30-530 and one volume oflgepal CO-630, both being non-ionic, alkyl phenoxy polyoxyethylene ethanol surfactants.

The emulsion was tested on afour-stand, high speed tandem mill for the cold reduction of l 48 inch wide steel stnp from 0.080 in. gage to 0.029 in. gage at a speed above 2000 ft. per minute. Reclaimed palm oil was used '1' a cleaner was applied to the steel strip prior to the last stand of rolls and, in this particular case, also to the upper back-up rolls of stands three and four. The steel strip emerged from the mill with no residual oil film, and came out of the box annealing operation very clean and entirely free of so-called dirt and carbon edge. Previous coils run in the same Work turn, using a commercial cleaner, had a greasy film and annealed dirty.

Example 11 A mill test similar to that of Example I was made, wherein the emulsion contained 1.0 part of tridecy'l alcohol in place of the iso-decyl alcohol of Example I. Two separate runs were made, with the emulsion having, in the first case, 50 parts of Water, and in the second case, 100 parts of water. Using the; emulsion containing 50 parts of water, steel strip was reduced from 0.080 in. gage to 0.015 in. gage, the emulsion being sprayed on the strip priorto the fourth stand. The rolling wa quite satisfactory and produced film-free coils that annealed clean. Similarly, using an emulsion containing 100 parts of water for dilution, steel was reduced to 0.017 inch gage. The strip from this latter test also annealed clean with no carbon edge or so-called dirt. In all cases, dirt was evaluated after annealing by a standard technique of holding a white paper toWel against the rapidly moving steel strip as it was unwound and fed to the skinpass (surface finishing) mill.

While in the examples, single alcohols have been used in the emulsion as the cleaning medium, the invention is not restricted to such use.' Mixtures of alcohols, of the class specified, may be used as the cleaner.

It should be pointed out that the amounts of water and alcohol, used in the cleaner mixture, need not be limited to those given in the several examples. The amount of water used may range from approximately 50 parts to as much as 200 parts, while the alcohol content may vary from 0.4 part to 10 parts, or, in other Words, a 50011 ratio of water to alcohol at the one extreme, to a ratio of :1 of water to alcohol at the other extreme. The ratios just given are weight ratios. While the composition in Example I was actually made on a volume basis, there is no significant difference in the ratios, as a practical matter, Whether given by weight or by volume. For example, in the composition. of Example I, 1.0 part by volume of iso-decyl alcohol would represent 0.835 part by Weight. The specific amounts of water and alcohol, to be used for any given cleaning operation, will depend on the nature of the material to be treated, i.e., the type of metallic surface and the type of lubricant used, as well as on the operating conditions, for example, the speed of travel in the case of rolled strip.

Certain organic solvents, for example kerosene or mineral spirits, may be mixed with the alcohol-Water emulsion. The addition of an organic solvent is effective in certain cases in increasing the fluidity of the detergent, while at the same time having no adverse effect on the etergent properties of the alcohol.

Another mill test, similar to those of Examples I and II, was run using a mixture of alcohols and a reduced quantity of emulsifier as follows:

Example III Parts (volume) Water 75 Iso-decyl alcohol 0.5 Tridecyl alcohol 0.5

practice to remove more of the rolling oil, and for this reason sprays of the cleaner mixture were directed onto both the top and bottom sides of the strip prior to stands three and four, and on the upper backup roll of number four stand. The strip was quite dry and free from oil as it came from the mill. The strip came out of the subsequent box annealing very clean without the use of any intermediate cleaning operation.

Satisfactory temporary emulsions can be made with the higher alcohols by using surfactants, or emulsifiers, other than those shown in Examples I, II and 111. Other compositions have been tested in a laboratory apparatus designed to compare the cleaning efficiency of various compositions on soiled or coated test panels. The apparatus has been used extensively to screen various cleaning compositions prior to utilizing them in actual mill testing. The results of the laboratory tests have been found to correlate well with actual mill results.

The test procedure consisted in allowing a heated quantity of dispersion to drop onto a steel panel which has been coated with used rolling oil containing iron soaps and polymers.

The apparatus consisted of a 250 ml. capacity glass separatory funnel wrapped with electrical heating tape to maintain a temperature of 100 C. in the test solutions, or dispersions. A spiral blade stirrer was used to keep the test material dispersed.

A standard volume of 100 ml. of test dispersion was heated to 100 C. and put into the heated separatory funnel while stirring was maintained therein. The stopcock was opened full and dispersion allowed to run out, it dropping a distance of exactly 24 inches onto a 3 in. by 6 in. soiled steel test panel inclined at an angle of 45. The point of impingement was one inch from the upper end of the panel. The area of a panel subject to cleaning by impingement, outward flow and run-off of the test solution amounted to from 13 to 15 square inches. A cleaned area of 13 square inches was considered excellent. The test panels were thinly coated with a mixture consisting of 8% lamp black and 92% of recovered, used tallowbased rolling oil containing the varnish-like degradation products formed by the heat and pressures of the mill. Lamp black was added merely for the purpose of rendering the coating readily visible. The degradation products included iron soaps and polymers formed from the oil. Such oil for this test was obtained from the used oil sludge in the oil sewer beneath the tandem mill. The sludge was dried and the oil extracted with diethyl ether.

The filtered and dried ether extract was much more tacky than the new oil, and extremely more resistant to its removal by proprietary cleaners and surfactants. The proprietary cleaners and all the common surfactants tested were able to clean only a small area at the point of immediate impingement of the stream on the panel. In most cases the result was a partial cleaning of from A to 3 squareinches. This used oil was considered more characteristic of that encountered in actual practice on the tandem mill. The oil was consequently used for coating the test panels rather than new undamaged oil which presents no particular removal problem.

As a control for the laboratory test examples, the composition given in Example I (mill test) was tried in the apparatus at a dilution of to 1. This resulted in a cleaned area of 13 square inches.

The previous examples (representing mill tests) used nonyl phenoxy polyoxyethylene ethanol compounds to cause the higher alcohols to form temporary emulsions capable of lasting up to the point of application at the strip surface. Other surface active compounds may be used to accomplish the same result without materially impairing the ability of these alcohols to clean metal surfaces. The following three examples successfully employed a different non-ionic, an anionic, and a cationic surfactant respectively to form a suitable temporary emulsion with the higher alcohol.

Example IV Example V Iso-decyl alcohol was mixed with 1% by weight of Santomerse D (Monsanto Chemical Company), an alkyl benzene sodium sulfonate, anionic surfactant. One volume of this mixture was diluted with 75 volumes of water and the resultant mixture tested on a coated panel as in Example IV. The resulting cleaned area was measured to be about 12.5 square inches.

Example VI Iso-decyl alcohol was mixed with 5% by weight of Hyamine 1622 (Rohm & Haas Company), para diisobutyl phenoxy ethoxy ethyl dimethyl benzyl ammonium chloride monohydrate, a cationic surfactant. One volume of this mixture was diluted with 75 volumes of water and tested as in Examples IV and V. The cleaned area amounted to about 13 square inches.

While my invention has been described as a method for the treatment of the surfaces of ordinary steel, it is also applicable in the cleaning of surfaces of stainless steel; The emulsion treatment is not confined to flat, or rolled surfaces, but may also be used in the removal of lubricant film from wire and other extruded metal articles. Another quite useful application is in the washing of cold-rolled steel strip prior to electrotinning, in which use the cleaning emulsion eliminates the necessity of an alkaline cleaner. 7

I claim:

1. The method of removing an oily lubricant film containing iron soaps from a steel surface coated with said film Which comprises applying to said coated surface an aqueous mixture consisting essentially of Water and a member. of the group consisting of m-terpineol, geraniol, mixtures of a-terpineol and geraniol, water-insoluble fatty alcohols having from 6 to 18 carbon atoms and mixtures of said fatty alcohols wherein the weight ratio of water to said member ranges from 500:1 to 5:1.

2. The method of removing anoily lubricant film con taining iron soaps from a steel surface coated with said film which comprises applying to said coated surface an aqueous mixture consisting essentially of Water and a member of the group consisting of a-terpineol, geraniol, mixtures of a-terpineol and geraniol, water-insoluble fatty alcohols having from 6 to 18 carbon atoms and mixtures of said fatty alcohols wherein the weight ratio of water to said member ranges from 400:1. to 5 :1.

3. The method of removing an oily lubricant film containing iron soaps from a steelsurface coated with said film which comprises applying to said coated surface an aqueous mixture consisting essentially of water and a water-insoluble fatty alcohol having from 6 to 18 carbon atoms wherein the weight" ratio of water to said alcohol ranges from 500:1 to 5:1.

4. The method of removing an oily lubricant film containing iron soaps from a steel surface coated with said film which comprises applying to said coated surface an aqueous mixture consisting essentially of water and decyl alcohol wherein the weight ratio of water to said alcohol ranges from 500:1 to 5:1.

5. The method of removing an oily lubricant film confilm which comprises applying to said coated surface an aqueous mixture consisting essentially of water and tridecyl alcohol wherein the weight ratio of water to said alcohol ranges from 500:1 to 5:1.

6. The method of removing an oily lubricant film containing iron soapsfrom a steel surface coated with said film which comprises applying to said coated surface an aqueous mixture consisting essentially of water and terpineol wherein the weight ratio of water to terpineol ranges from 500:1 to 5:1.

7. The method of removing an oily lubricant. film containing iron soaps from a steel surface coated with said film which comprises applying to said coated surface an aqueous mixture consisting essentially of water and from 0.20% to 20.0% by weight of a member of the group consisting of a-terpineol, geraniol, mixtures of a-terpineol and geraniol, water-insoluble fatty alcohols having from 6 to 18 carbon atoms and mixtures of said fatty alcohols.

8. The method of removing an oily lubricant film containing iron soaps from a steel surface coated with said fihn which comprises applying to said coated surface an aqueous mixture consisting essentially of from 50 to 200 parts of water and from 0.4 to 10 parts by Weight of a member of the group consisting of a-terpineol, geraniol, mixtures of a-terpineol and geraniol, water-insoluble fatty alcohols having from 6 to 18 carbon atoms and mixtures of said fatty alcohols.

9. The method of removing an oily lubricant film containing iron soaps from a steel surface coated with said film which comprises applying to said "coated surface an aqueous mixture consisting essentially of from 50 to 200 parts by weight of water, from 0.4 to 10 parts by weight of a member of the group consisting of m-terpineol, geraniol, mixtures of oc-terpineol and geraniol, water insoluble fatty alcohols having from 6 to 18 carbon atoms and mixtures of said fatty alcohols, and an emulsifier to produce a non-stable emulsion with said water and said member.

10. The method of removing an oily lubricant film containing iron soaps from a steel surface coated with said film which comprises applying to said coated surface an aqueous mixture consisting essentially of from 50 to 200 parts by weight of water, from 0.4 to 10 parts by weight of a member of the group consisting of a-terpineol, geraniol, mixtures of a-terpineol and geraniol, Water insoluble fatty alcohols having from 6 to 18 carbon atoms and mixtures of said fatty alcohols, and a non-ionic emulsifier to produce a non-stable emulsion with said water and said member.

11. The method of removing an oily lubricant film containing iron soaps from a steel surface coated with said film which comprises applying to said coated surface an aqueous mixture consisting essentially of from 50 to 200 References Cited in the file of this patent UNITED STATES PATENTS 2,032,174 Johnson Feb. 25, 1936 2,162,656 Warrington June 13, 1939 2,290,908 Gunning July 28, 1942 2,350,145 Backoff et al May 30, 1944 2,356,254 Lehmann et al. Aug. 22, 1944 FOREIGN PATENTS 573,145 Great Britain Nov. 8, 1945 706,407 Great Britain "nun"..- Mar. 31, 1954 

1. THE METHOD OF REMOVING AN OILY LUBRICANT FILM CONTAINING IRON SOAPS FROM A STEEL SURFACE COATED WITH SAID FILM WHICH COMPRISES APPLYING TO SAID COATED SURFACE AN AQUEOUS MIXTURE CONSISTING ESSENTIALLY OF WATER AND MEMBER OF THE GROUP CONSISTING OF A-TERPINEOL, GERANIOL, MIXTURES OF A-TERPINEOL AND GERANIOL, WATER-INSOLUBLE FATTY ALCOHOLS HAVING FROM 6 TO 18 CARBON ATOMS AND MIXTURES OF SAID FATTY ALCOHOLS WHEREIN THE WEIGHT RATIO OF WATER TO SAID MEMBER RANGES FROM 500:1 TO 5:1. 